Healing magic is different that fire resistance. I can understand a Fire Elemental being healed by fire, but someone of Flesh and Blood should not be healed by Fire, regardless of their resistance to being burned. To heal Flesh and Blood requires a different kind of magic, not negative burning.
And yeah I know it's a single player game and I know I can just make the game difficult on myself, but I'd rather game logic be logical. But to each their own I guess.
I agree with this. Damaging environmental effects healing certain types of monsters makes a lot of sense to me, but it's probably very hard to balance fights if it works that way for the player too. So, a cap on resistances is a Good Thing (tm).
What's of course not good is that there were some oversights like the Zombie trait. As that's a special case for only one type of damage and costs one trait, I'm fairly sure the trait will be fixed. Other talents may well have to be re-evaluated as well.
There needs to be some way to reach at least 100% resist just because there are so many spells and talents that rely on standing in the middle of damaging terrain. It's not just Zombie, it's also Elemental Affinity, Explode, Storm, Self-Immolation, so on and so forth.
There are also spells that provide elemental shields or immunity against related status effects. You'd still get some damage but wouldn't have to suffer the elemental side-effects. Although in the case of shields, I wouldn't mind if they set the resistance to a fixed 100% instead of reducing partial damage ...
All that said, Larian should maybe have provided free respecs in some form as is usual in MMOs when Talents change a lot. But the resistance change in itself is, IMO, good for the game.
